If the template has a separate documentation page (usually called "Template:template name/doc"), add

[[Category:Date-computing templates based on current time]]

to the <includeonly> section at the bottom of that page. Otherwise, add

<noinclude>[[Category:Date-computing templates based on current time]]</noinclude>

to the end of the template code, making sure it starts on the same line as the code's last character.

This category contains utility templates used to compute dates and time values. Despite their internal design, they are built for maximum reusability in various contexts, so the syntax to use them is very simple, and each of these templates is documented with examples of use and return values. These templates are useful for auto-categorization, or for creating navigation panels in articles the names of which include date elements.